Professor Oak is the first NPC (non-person character) you talk to in the game at the start of the game. He will give you a starter once you start the game. His lab has many things, including a picture that shows his favourite Pokemon, Dragonite. You can also find Professor Oak in Saffron City where if you have 300 Pokemon in your Pokedex, Professor Oak will give you a Heatran.
Your starter Pokémon is free. However, you must have 300 Pokedex entries to obtain a Heatran from him.